gambatte_qt/framework: add common to dependpath

fixes no recompilation when touching common headers
gambatte_qt: simplify .pro files HEADER deps by using wildcards

also fixes some missing header deps.
gambatte_qt/framework: openbsd-*:LIBS += -lusbhid -lossaudio
gambatte_qt/ossengine: use /dev/audio on OpenBSD by default

requested by anthonyjbentley.
libgambatte/sound/channel4: formatting/readability/dead code
libgambatte/sound/channel3: formatting/readability
libgambatte/sound/channel2: formatting/readability
libgambatte/sound/channel1: formatting/readability
libgambatte/sound/dutyunit: formatting/readability
libgambatte/sound/length_counter: formatting/readability
libgambatte/sound: formatting/readability
libgambatte/cpu: formatting/readability
libgambatte/cpu: drop f/from_f macros
libgambatte/ppu: superflous mask
libgambatte/cpu: less magic HF2 constants
libgambatte/gambatte: formatting/readability
libgambatte: use ptrdiff_t to represent pitch
common/videolink: use ptrdiff_t to represent pitch
gambatte_sdl: use ptrdiff_t to represent pitch
gambatte_qt: use ptrdiff_t to represent pitch